This is the original Mission 774 tonearm, designed by John Bicht (of Versa Dynamics fame). It utilises some unique design features such as fluid damping, interchangeable arm wand and direct cartridge clamping. The latter avoid issues with head shell vibration. The arm fits a standard SME mount. There are other versions of the Mission 774, but the later ones were low cost version (e.g. 774LC with Linn style mount). This example here is in superb condition, with original box and accessories. Well worth checking out.
In 1983 (when priced at £157) Hi-Fi Choice magazine said:
Arguably one of the finest low mass tonearms; the Mission 774 is distinguished by its dry and controlled neutrality; upper midband was slightly hard; offered a fine transient performance